Reduction In Biological Activity Research Articles

Investigating the transcriptomic variances in two phases Ecytonucleospora hepatopenaei (EHP) in Litopenaeus vannamei

This study explores the transcriptomic differences in two distinct phases of Ecytonucleospora hepatopenaei (EHP) in Litopenaeus vannamei, a crucial aspect in shrimp health management. We employed high-throughput sequencing to categorize samples into two phases, 'Phase A' and 'Phase B', defined by the differential expression of PTP2 and TPS1 genes. Our analysis identified 2057 genes, with 78 exhibiting significant variances, including 62 upregulated and 16 downregulated genes. Enrichment analyses via GO and KEGG pathways highlighted these genes' roles in cellular metabolism, signal transduction, and immune responses. Notably, genes like IQGAP2, Rhob, Pim1, and PCM1 emerged as potentially crucial in EHP's infection process and lifecycle. We hypothesize that these genes may influence trehalose metabolism and glucose provision, impacting the biological activities within EHP during different phases. Interestingly, a lower transcript count in 'Phase A' EHP suggests a reduction in biological activities, likely preparing for host cell invasion. This research provides a foundational understanding of EHP infection mechanisms, offering vital insights for future studies and therapeutic interventions.

High-Throughput Transcriptomics of Water Extracts Detects Reductions in Biological Activity with Water Treatment Processes.

The presence of numerous chemical contaminants from industrial, agricultural, and pharmaceutical sources in water supplies poses a potential risk to human and ecological health. Current chemical analyses suffer from limitations, including chemical coverage and high cost, and broad-coverage in vitro assays such as transcriptomics may further improve water quality monitoring by assessing a large range of possible effects. Here, we used high-throughput transcriptomics to assess the activity induced by field-derived water extracts in MCF7 breast carcinoma cells. Wastewater and surface water extracts induced the largest changes in expression among cell proliferation-related genes and neurological, estrogenic, and antibiotic pathways, whereas drinking and reclaimed water extracts that underwent advanced treatment showed substantially reduced bioactivity on both gene and pathway levels. Importantly, reclaimed water extracts induced fewer changes in gene expression than laboratory blanks, which reinforces previous conclusions based on targeted assays and improves confidence in bioassay-based monitoring of water quality.

The interactions between Reactive Black 5 and human serum albumin: combined spectroscopic and molecular dynamics simulation approaches.

Azo dyes are made in significant amounts annually and released into the environment after being employed in the industry. There are some reports about the toxic effects of these dyes on several organisms. Thus, the textile dye Reactive Black 5 (RB5) has been examined for its cytotoxic effects on the human serum albumin (HSA) structure. Molecular interaction between RB5 and HSA indicated the combination of docking methods, molecular dynamic simulation, and multi-spectroscopic approaches. HSA's intrinsic fluorescence was well quenched with enhancing RB5 level, confirming complex formation. Molecular dynamics (MD) simulation was done to study the cytotoxic effects of RB5 and HSA conformation. Molecular modeling revealed that the RB5-HSA complex was stabilized by hydrogen bonds and van der Waals interactions. The results of molecular docking revealed that the binding energy of RB5 to HSA was - 27.94kJ/mol. The change in secondary structure causes the annihilation of hydrogen bonding networks and the reduction of biological activity. This research can indicate a suitable molecular modeling interaction of RB5 and HAS and broaden our knowledge for azo dye toxicity under natural conditions.

Mutation of Methionine to Asparagine but Not Leucine in Parathyroid Hormone Mimics the Loss of Biological Function upon Oxidation.

Human parathyroid hormone (PTH) is an 84-amino acid peptide that contains two methionine (Met) residues located at positions 8 and 18. It has long been recognized that Met residues in PTH are subject to oxidation to become Met sulfoxide, resulting in a decreased biological function of the peptide. However, the mechanism of the lost biological function of PTH oxidation remains elusive. To characterize whether the shift from the hydrophobic nature of the native Met residue to the hydrophilic nature of Met sulfoxide plays a role in the reduction of biological activity upon PTH oxidation, we conducted in silico and in vitro site-directed mutagenesis of Met-8 and Met-18 to the hydrophilic residue asparagine (Asn) or to the hydrophobic residue leucine (Leu) and compared the behavior of these mutated peptides with that of PTH oxidized at Met-8 and/or Met-18. Our results showed that the biological activity of the Asn-8 and Asn-8/Asn-18 mutants was significantly reduced, similar to Met-8 sulfoxide and Met-8/Met-18 sulfoxide analogues, while the functions of Asn-18, Leu-8, Leu-8/Leu-18 mutants, or Met-18 sulfoxide analogues were similar to wild-type PTH. This is rationalized from molecular modeling and immunoprecipitation assay, demonstrating disruption of hydrophobic interactions between Met-8 and Met-18 of PTH and type-1 PTH receptor (PTHR1) upon mutation or oxidation. Thus, these novel findings support the notion that the loss of biological function of PTH upon oxidation of Met-8 is due, at least in part, to the conversion from a hydrophobic to a hydrophilic residue that disrupts direct hydrophobic interaction between PTH and PTHR1.

Short-term effects of repeated application of solid digestate on soil C and N dynamics and CO2 emission in a clay soil olive (Olea europaea L.) orchard

Olive orchards cultivation often has to face several soil degradation phenomena like organic matter depletion, reduction of biological activity and generalised loss of fertility. In these contexts, agricultural solid digestate has shown promising results in restoring fertility, although its sustainability has not been fully assessed. Therefore, to evaluate its common use in this agroecosystem, we conducted a field experiment to study the short-term effects of repeated amendment with solid anaerobic digestate on the integral fertility of an olive orchard grown in a clayey soil in Southern Italy. We compare the following treatments: unamended control, one-year and two-year solid digestate amendment application. During the experiment, we assessed changes in soil fertility and dynamics of C and N pools by measuring a set of chemical, biochemical and soil eco-physiological variables and by monitoring CO2 fluxes at field scale. Results showed growing benefits from single to repeated treatment with solid digestate, compared to the control, such as an increase of soil soluble C and N forms, organic matter and microbial pools with higher microbial activity and, despite a relative increase in CO2 field emission, microbial efficiency, thus proving to be a sustainable management for olive orchard agroecosystems.

Functional characterisation of two receptor interaction determinants in human thymic stromal lymphopoietin.

Thymic stromal lymphopoietin (TSLP) is a pro-inflammatory cytokine with important pathological roles in Asthma bronchiale, malignant tumours and other diseases. The heterodimeric human TSLP receptor (hTSLPR) consists of the TSLP-binding subunit (TSLPRα) and the IL-7Rα-subunit. We studied the properties of hTSLP variants with mutations in their bipartite interaction interface towards IL-7Rα. One mutant (T46D/K101D) showed only mild impairment in receptor affinity but a massive reduction in biological activity. To facilitate the future development of hTSLP mutants with drug properties, we have devised a eukaryontic cytokine display assay with activity read-out and intrinsic genotype-phenotype coupling.

Soil Sealing on Example of the Jedrzychow Residential Area in Zielona Gora, Poland

The progressing urbanization leads to the growth of buildings within the cities and taking up new areas for investments. Uncontrolled urban sprawl entails a number of consequences resulting in the soil sealing of the areas which has been permeable so far. Cutting off deeper soil layers from gas exchange and access to water causes a reduction in biological activity and biodiversity. That is why EU considers soil sealing as one of the main problems of the 21st century. The paper attempts to analyze the progressing urbanization on the one of the Zielona Góra housing estates - Jędrzychów Residential Area.

Organometallic nucleoside analogues: effect of the metallocene metal atom on cancer cell line toxicity.

A new chiral organometallic nucleoside analogue containing ruthenocene is reported, in which alkylthymine and alkylhydroxyl groups are attached in adjacent positions on one cyclopentadienyl ring. The synthetic procedures for this metallocene derivative and two control compounds are described, along with their characterisation by cyclic voltammetry and X-ray crystallography. Their biological activities in a human pancreatic cancer cell line (MIA-Pa-Ca-2) were significantly lower than those of three previously reported analogous ferrocene compounds, indicating that the choice of metallocene metal atom (Fe or Ru) plays a pivotal role in determining the anticancer properties of these nucleoside analogues, which in turn suggests a different mode of action from that of a conventional nucleoside analogue.

Combination of RTS,S and Pfs25-IMX313 Induces a Functional Antibody Response Against Malaria Infection and Transmission in Mice.

The last two decades saw a dramatic reduction in malaria incidence rates, but this decrease has been stalling recently, indicating control measures are starting to fail. An effective vaccine, particularly one with a marked effect on disease transmission, would undoubtedly be an invaluable tool for efforts to control and eliminate malaria. RTS,S/AS01, the most advanced malaria vaccine to date, targets the parasite before it invades the liver and has the potential to prevent malaria disease as well as transmission by preventing blood stage infection and therefore gametocytogenesis. Unfortunately efficacy in a phase III clinical trial was limited and it is widely believed that a malaria vaccine needed to contain multiple antigens from different life-cycle stages to have a realistic chance of success. A recent study in mice has shown that partially efficacious interventions targeting the pre-erythrocytic and the sexual lifecycle stage synergise in eliminating malaria from a population over multiple generations. Hence, the combination of RTS,S/AS01 with a transmission blocking vaccine (TBV) is highly appealing as a pragmatic and powerful way to increase vaccine efficacy. Here we demonstrate that combining Pfs25-IMX313, one of the TBV candidates currently in clinical development, with RTS,S/AS01 readily induces a functional immune response against both antigens in outbred CD1 mice. Formulation of Pfs25-IMX313 in AS01 significantly increased antibody titres when compared to formulation in Alhydrogel, resulting in improved transmission reducing activity in standard membrane feeding assays (SMFA). Upon co-formulation of Pfs25-IMX313 with RTS,S/AS01, the immunogenicity of both vaccines was maintained, and functional assessment of the induced antibody response by SMFA and inhibition of sporozoite invasion assay (ISI) showed no reduction in biological activity against parasites of both lifecycle stages. Should this findings be translatable to human vaccination this could greatly aid efforts to eliminate and eventually eradicate malaria.

Adults with eosinophilic oesophagitis identify symptoms and quality of life as the most important outcomes.

Well informed patients who are in cohesive partnership with physicians and who have realistic expectations towards therapy are more likely to be adherent, which results in better disease control. To assess which therapy goals adults with eosinophilic oesophagitis consider relevant. Following refinement during three focus groups, a study brochure and questionnaire were sent to 148 patients. Patients ranked the importance (five levels) of short-term (in the next 3months) and long-term (≥1year) treatment effect on symptoms, quality of life (QoL), histologically-detected inflammation and fibrosis, endoscopically-detected inflammation, and stricture formation as well as achieving histological remission while asymptomatic. Patients' characteristics associated with treatment goals were identified using logistic regression. Of 109 respondents (mean age 43years), 85 were men. Over 90% chose symptoms and QoL improvement as important short- and long-term therapy goals. A greater proportion attributed more importance to long-term reduction in endoscopic (90% vs 73%, P<0.001) and histological (81% vs 62%, P=0.002) inflammation, and histologically-detected fibrosis (79% vs 64%, P=0.018) when compared to short-term reduction in these features. Patients (88%) ranked achieving histological remission while being asymptomatic as important. Gender, therapy use, education level, QoL, symptom severity, and history of dilation were associated with patients' choice of treatment goals. Patients attributed most importance to improvement in symptoms and QoL. Reduction in biological activity was judged less important, but more relevant in the long- compared to the short-term.

Effect of the Various Steps in the Processing of Human Milk in the Concentrations of IgA, IgM, and Lactoferrin.

Human milk immune components are unique and important for the development of the newborn. Milk processing at the Human Milk Banks (HMB), however, causes partial destruction of immune proteins. The objective of this study was to determine the effects that heating during the milk processing procedure at the HMB had on the concentrations of IgA, IgM, and lactoferrin at three critical points in time. Fifty milk samples (150 mL) were collected from voluntary donors at the HMB at the Hospital Nacional Pedro de Bethancourt, located in Antigua Guatemala. Samples from three critical points in time during the milk processing procedure were selected for analysis: freezing/thawing I, freezing/thawing II, and pasteurization. IgA, IgM, and lactoferrin concentrations were determined during each critical point and compared with a baseline concentration. After milk processing, IgA, IgM, and lactoferrin mean concentrations were reduced by 30.0%, 36.0%, and 70.0%, respectively (p < 0.001). Reduction of biological activity was mainly attributed to pasteurization for IgA and lactoferrin (p < 0.001); the first freezing/thawing processes before pasteurization showed no significant reduction difference between mean concentrations of IgA (p = 0.160) and lactoferrin (p = 0.345) but showed a significant effect on IgM concentration (p = 0.016), and the second freezing/thawing procedure only showed a significant effect on IgA (p < 0.001). The effects of milk processing on the immune proteins that were evaluated in this study demonstrated a significant reduction.

Selective Phosphodiesterase Inhibitors for Psoriasis: Focus on Apremilast.

Phosphodiesterase (PDE) 4 participates in regulating the inflammatory response by degrading cyclic adenosine 3′,5′-monophosphate (cAMP), a key second messenger. Inhibition of PDE4 increases the intracellular cAMP level, which in turn results in a reduction in inflammatory mediators and an increase in anti-inflammatory mediators. Immune-modulating effects of PDE4 inhibitors have been investigated in a number of inflammatory conditions, such as asthma, atopic dermatitis, chronic obstructive pulmonary disease, Behçet’s disease, psoriasis, and psoriatic arthritis. Apremilast, a selective PDE4 inhibitor, has been shown to block the production of pro-inflammatory cytokines (interferon-γ, tumor necrosis factor-α, interleukin [IL]-12, IL-17, and IL-23), which are the key players in the pathogenesis of psoriasis. Increased intracellular cAMP levels result in a range of anti-inflammatory effects on numerous cell lines. A decrease in pro-inflammatory activity has been shown to result in a reduced psoriasiform response in preclinical in vivo models of psoriasis, and reduction of biologic activity in a pilot study in humans. The efficacy and safety of apremilast in the treatment of psoriasis have been demonstrated in phase II and III clinical trials. Apremilast demonstrated efficacy in reducing the severity of moderate to severe plaque psoriasis. Treatment with apremilast was well tolerated, with generally mild gastrointestinal complaints, which occurred early in the course of the treatment and resolved over time, and there was no requirement for laboratory test monitoring. These results make apremilast an attractive therapeutic option for plaque psoriasis.

Periplasmic Expression of TNF Related Apoptosis Inducing Ligand (TRAIL) in E.coli.

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), a member of TNF family, is an interesting ligand which selectively induces apoptosis in tumor cells and, therefore, it has been developed for cancer therapy. This ligand has been produced by various hosts such as E.coli. However, protein expression in E.coli cytoplasm leads to problems such as incorrect folding, reduction in biological activity, inclusion body formation, and sophisticated downstream. The aim of this study is to develop an expression system for the production of recombinant TRAIL secreted to the E.coli periplasm instead of cytoplasm. By using Overlapping Extension PCR, an OmpA signal sequence was fused to TRAIL cDNA and OmpA-TRAIL fragment was then cloned in pET-22b plasmid. This construct was confirmed by PCR and DNA sequencing. Promoter was induced in E.coli BL21 (DE3) and periplasmic expressed proteins were released using osmotic shock procedure. SDS-PAGE analysis showed that about 37% of recombinant TRAIL was transferred into the periplasm and its identity was confirmed by western blot analysis. Finally, the cytotoxic activity of TRAIL against HeLa cell line was confirmed by using MTT assay. The results demonstrate that our expression system may be useful for the production of TRAIL in the periplasmic space.

Structural Requirements of Strigolactones for Shoot Branching Inhibition in Rice and Arabidopsis.

The structural requirements of strigolactones (SLs) involved in germination induction of root parasitic plants and hyphal branching in arbuscular mycorrhizal (AM) fungi have been extensively studied. However, our knowledge of the requirements of SLs involved in shoot branching inhibition in plants is still limited. To address this question, we investigated the structure-activity relationships of SLs in shoot branching inhibition in rice and Arabidopsis. SLs possess a four-ring structure, with a tricyclic lactone (ABC-rings) connected to a methylbutenolide part (D-ring) via an enol ether bridge. Here, we show that the the (R) configuration at C-2', which determines the steric position of the D-ring relative to the enol ether olefin bond, is critical for the hormonal activity in rice. Replacement of the enol ether moiety by an alkoxy or imino ether resulted in a severe reduction in biological activity in rice. Moreover, yeast two-hybrid experiments using a possible SL receptor, DWARF14 (D14), and a repressor in the SL signaling pathway, DWARF53 (D53), showed that D14 can interact with D53 in the presence of (2'R) stereoisomers of SLs, but not (2'S) stereoisomers, suggesting that the stereostructure of SLs is crucial for the interaction of these proteins. When GR5, an AB-ring-truncated analog, was applied to the hydroponic culture medium, strong inhibition of shoot branching was observed both in rice and in Arabidopsis. However, GR5 was only weakly active when directly applied to the axillary buds of Arabidopsis. Our results indicate that the difference in plant species and application methods greatly influences the apparent SL biological activity.

Condensed Tannins in Sainfoin: Composition, Concentration, and Effects on Nutritive and Feeding Value of Sainfoin Forage

ABSTRACTLegume forage is the most economical source of nutrients for ruminants. Sainfoin (Onobrychis viciifolia Scop.) is high nutritive forage growing worldwide and possesses polyphenolics including condensed tannins (CT) that contribute to some of its superior nutritional properties such as improved protein utilization, bloat‐free, and anthelmintic characteristics. This review attempts to capture the latest research in characterizing the impact of polyphenolics on the feeding value of sainfoin with an emphasis on CT. Sainfoin contains a diverse array of polyphenolics and its CT content declines as the plant matures, with an increase in the degree of polymerization and a decreasing proportion of prodelphinidins, resulting in a reduction in biological activity. This forage is best to be utilized between bud to flowering stage to balance the biological activity of CT and biomass yield. Incorporation of sainfoin into alfalfa (Medicago sativa L.) pasture has been effective in reducing alfalfa pasture bloat due to the presence of CT. New sainfoin populations suitable for survival in high‐performance grazing systems have been developed and have demonstrated superior anti bloat activity due to the increased grazing persistence. Fresh sainfoin is the best feed for cattle for maximum effect of CT, but if it needs to be preserved then hay would be better than silage in terms of preservation of the biological activity of CT. Although greater CT content is desirable for this forage in terms of antibloat and antiparasitic activity, sainfoin with CT concentration at about 50 g kg−1 dry matter (DM) offer the best feed value.

Increased gene delivery efficiency and specificity of a lipid-based nanosystem incorporating a glycolipid.

Hepatocellular carcinoma (HCC) is the third most common cause of death related to cancer diseases worldwide. The current treatment options have many limitations and reduced success rates. In this regard, advances in gene therapy have shown promising results in novel therapeutic strategies. However, the success of gene therapy depends on the efficient and specific delivery of genetic material into target cells. In this regard, the main goal of this work was to develop a new lipid-based nanosystem formulation containing the lipid lactosyl-PE for specific and efficient gene delivery into HCC cells. The obtained results showed that incorporation of 15% of lactosyl-PE into liposomes induces a strong potentiation of lipoplex biological activity in HepG2 cells, not only in terms of transgene expression levels but also in terms of percentage of transfected cells. In the presence of galactose, which competes with lactosyl-PE for the binding to the asialoglycoprotein receptor (ASGP-R), a significant reduction in biological activity was observed, showing that the potentiation of transfection induced by the presence of lactosyl-PE could be due to its specific interaction with ASGP-R, which is overexpressed in HCC. In addition, it was found that the incorporation of lactosyl-PE in the nanosystems promotes an increase in their cell binding and uptake. Regarding the physicochemical properties of lipoplexes, the presence of lactosyl-PE resulted in a significant increase in DNA protection and in a substantial decrease in their mean diameter and zeta potential, conferring them suitable characteristics for in vivo application. Overall, the results obtained in this study suggest that the potentiation of the biological activity induced by the presence of lactosyl-PE is due to its specific binding to the ASGP-R, showing that this novel formulation could constitute a new gene delivery nanosystem for application in therapeutic strategies in HCC.

Changes in hormone and stress-inducing activities of municipal wastewater in a conventional activated sludge wastewater treatment plant

Conventional municipal wastewater treatment plants do not efficiently remove contaminants of emerging concern, and so are primary sources for contaminant release into the aquatic environment. Although these contaminants are present in effluents at ng-μg/L concentrations (i.e. microcontaminants), many compounds can act as endocrine disrupting compounds or stress-inducing agents at these levels. Chemical fate analyses indicate that additional levels of wastewater treatment reduce but do not always completely remove all microcontaminants. The removal of microcontaminants from wastewater does not necessarily correspond to a reduction in biological activity, as contaminant metabolites or byproducts may still be biologically active. To evaluate the efficacy of conventional municipal wastewater treatment plants to remove biological activity, we examined the performance of a full scale conventional activated sludge municipal wastewater treatment plant located in Guelph, Ontario, Canada. We assessed reductions in levels of conventional wastewater parameters and thyroid hormone disrupting and stress-inducing activities in wastewater at three phases along the treatment train using a C-fin assay. Wastewater treatment was effective at reducing total suspended solids, chemical and biochemical oxygen demand, and stress-inducing bioactivity. However, only minimal reduction was observed in thyroid hormone disrupting activities. The present study underscores the importance of examining multiple chemical and biological endpoints in evaluating and monitoring the effectiveness of wastewater treatment for removal of microcontaminants.

Bioavailability and fate of sediment-associated trenbolone and estradiol in aquatic systems

Endocrine disrupting effects in aquatic organisms have been observed in systems influenced by steroid hormones. Associating endocrine disruption with aqueous concentrations of steroids alone may overlook the influence of source–sink dynamics in sediments on steroid hormone bioavailability. The objective of this study was to determine the fate of 17β-estradiol and 17β-trenbolone in two field sediments and to evaluate the corresponding bioavailability of the compounds to the fathead minnow (Pimephales promelas). Steroid fate was evaluated using analytical chemistry and verified by assessing the biological activity using yeast based in vitro assays. Effective bioavailability of the steroids was inferred from changes in hepatic vitellogenin expression (increased expression in males exposed to 17β-estradiol, and reduced expression in females exposed to 17β-trenbolone). In experiments conducted with 17β-estradiol, no induction of hepatic vitellogenin mRNA expression was observed in male fish exposed to sediment-associated 17β-estradiol. In contrast, female minnows exposed to sediment-associated 17β-trenbolone experienced significant reductions in hepatic vitellogenin compared to negative controls. In both systems, the parent compounds were shown to degrade rapidly to the more persistent metabolites, estrone and trendione, both of which were found predominantly associated with the sediments. Results from the yeast estrogen screen indicate a reduction in biological activity as biotransformation of 17β-estradiol occurs; results from the yeast anti-estrogen screen were inconclusive and unable to substantiate 17β-trenbolone fate in aquatic systems. Collectively, these data support the contention that steroid hormones associated with the sediment can become bioavailable to fish, and that sediment characteristics influence the observed bioavailability of these compounds.

Novel application of high pressure processing for the production of shellfish toxin matrix reference materials

The production of homogeneous and stable matrix reference materials for marine biotoxins is important for the validation and implementation of instrumental methods of analysis. High pressure processing was investigated to ascertain potential advantages this technique may have in stabilising paralytic shellfish poisoning toxins in shellfish tissues compared to untreated materials. Oyster tissues were subjected to a range of different temperatures and pressures, with results showing a significant reduction in biological activity in comparison to control samples, without significantly altering toxin profiles. Tissue subjected to pressures >600 MPa at 50 °C was assessed for homogeneity and stability. The sample homogeneity was determined using a pre-column oxidation LC-FLD method and shown to be within accepted levels of within batch repeatability. Short and long-term stability studies were conducted over a range of temperatures, with analysis by pre and post column oxidation LC-FLD demonstrating improved stability of toxins compared to the untreated materials and with epimerisation of toxins also notably reduced in treated materials. This study confirmed the technique of high pressure processing to improve the stability of PSP toxins compared to untreated wet tissues and highlighted its applicability in reference material preparation where removal of biological activity is of importance.

Impact of Wastewater Treatment Configuration and Seasonal Conditions on Thyroid Hormone Disruption and Stress Effects in Rana catesbeiana Tailfin

Improved endocrine disrupting compound (EDC) removal is desirable in municipal wastewater treatment plants (MWWTPs) although increased removal does not always translate into reduced biological activity. Suitable methods for determining reduction in biological activity of effluents are needed. In order to determine which MWWTPs are the most effective at removing EDC activities, we operated three configurations of pilot sized biological reactors (conventional activated sludge, CAS; nitrifying activated sludge, NAS; and biological nutrient removal, BNR) receiving the same influent under simulated winter and summer conditions. As frogs are model organisms for the study of thyroid hormone (TH) action, we used the North American species Rana catesbeiana in a cultured tadpole tailfin (C-fin) assay to compare the effluents. TH-responsive (thyroid hormone receptors alpha (thra) and beta (thrb)) and stress-responsive (superoxide dismutase, catalase, and heat shock protein 30) mRNA transcript levels were examined. Effluents infrequently perturbed stress-responsive transcript abundance but thra/thrb levels were significantly altered. In winter conditions, CAS caused frequent TH perturbations while BNR caused none. In summer conditions, however, BNR caused substantial TH perturbations while CAS caused few. Our findings contrast other studies of seasonal variations of EDC removal and accentuate the importance of utilizing appropriate biological readouts for assessing EDC activities.